// Encyclopedia

A very popular message broadcasting system that lets anyone send alphanumeric text messages up to 140 characters in length to a list of followers. Launched in 2006, Twitter was designed as a social network to keep friends and colleagues informed throughout the day. However, it became widely used for commercial and political purposes to keep customers, voters and fans up-to-date as well as to encourage feedback.

After establishing a Twitter account at www.twitter.com, individuals can import their e-mail addresses as well as use the Twitter search to locate and invite people. Twitter messages ("tweets") can be made public and sent to anyone requesting the feed, or they can be sent only to approved followers.

Messages can be sent and received via cellphone text messaging (SMS), the Twitter Web site or a third-party Twitter application. To follow a Twitter feed, the Twitter site and feed name become the URL; for example, Microsoft's Twitter feed is www.twitter.com/microsoft.

Forward that Tweet (Retweet)
Twitter becomes a viral conduit when users receive an interesting message and forward it to their followers. The ease of retweeting can quickly build large audiences. See retweet.

Replies and Direct Messages (DMs)
Initially a one-way broadcast from writer to follower, Twitter added a reply function that turned Twitter into a discussion group service.

Tweets can also be private. Writers can send followers a private message called a "direct message" (DM), and followers can do likewise. Followers can also delete the DMs they sent, making them disappear from the writer's inbox. In July 2015, the length of a DM was increased from 140 to 10,000 characters.

@ Signs and # Hashtags
When someone replies to a Twitter posting, they use their Twitter account name preceded by an @ sign; for example, "@JohnDoe."

A hashtag is a # prefix used to identify any topic so that it can be searched as a group. Hashtags are created for all major entities such as organizations, sports teams and political parties; however, they can be created for anything. For example, people commenting about a Twitter event in New York added the hashtag #nyctweetup in their postings, and all those messages could be viewed as a group by searching for #nyctweetup.

From Mobile Blogging to Microblogging
Twitter expanded "mobile blogging," the process of updating a blog from a cellphone, into updating a short activities blog (the "microblog") and immediately sending the update to followers. For more Twitter vocabulary, see Twitterese. See Vine and microblog.